Currently, there are a number of systems known and utilized for installing rivets in belt fasteners for coupling portions of a conveyor belt. In a simple form, a conveyor belt is a loop formed by a strip of conveyor belt material having two ends that are connected or coupled together. The connection or coupling is referred to as a belt splice, particularly when the connection is used to repair a broken portion of the belt. The belt material is often formed from a relatively hard, though flexible, rubber material and a number of layers typically including at least one webbing layer. The rubber provides flexibility and rigidity while the webbing layer minimizes or controls stretching, for instance. In this manner, the belt material is formed so as to maintain a general length and shape, particularly when installed on a pulley system and stressed during service.
The service demands of the conveyor belt require a relatively strong, yet flexible, connection or splice between the belt ends. Accordingly, the ends are commonly coupled, hinge-like, by opposed belt fasteners which are then threaded or coupled with a hinge pin.
To accept the hinge pin, the belt fasteners form a general U-shape or V-shape so they have has opposed side portions connected by a bend. The belt fasteners are connected to the belt ends with rivets having a head against a first side portion of the belt fastener, a shank passing through an opening in the first side portion of the belt fastener and through the belt material, and a swage end passing through an opening in a second side portion of the belt fastener and deformed around the opening.
The secured belt fasteners thus act as hinge knuckles. Each belt end has one or more belt fasteners secured with the belt so that the bend of the U-shape provides a lateral passage. The belt fasteners of opposite belt ends are positioned so that their respective lateral passages are aligned for receiving the hinge pin therein.
Optimal belt performance is related to proper connection between the belt ends and, hence, between the belt fasteners with the belt ends. The thickness of various belts may range, for instance, from one-eighth of an inch to over an inch. The rivets are provided with a frangible or releasable pilot nail shank for perceiving the belt material as the rivet is driven through. For driving, a central longitudinal axis of the rivet is aligned with the openings in the first and second opposed side portions of the belt fastener and then driven through. The driving not only drives the rivet through the belt material but also swages the rivet around the second opening. This requires a significant amount of force which, if not properly applied, may result in misalignment of the rivets with the belt fastener openings. That is, if the rivet is not started in the proper plane or at the proper angle, and is struck by this large force, it will miss the opening in the second side portion.
One manner known for aligning the rivets prior to and during driving is utilizing a guide block. The known guide block is formed of rubber or the like with one or more pilot holes. The guide block pilot is placed over the belt fastener so that the pilot holes are aligned with belt fastener openings. Each pilot hole is tapered inwardly so that the rivet is generally constrained and directed towards a center point of the belt fastener openings as the rivet is being driven, the lowest portion of the pilot hole being smaller than the pilot nail shank, which itself is smaller than the rivet head that also must pass through the guide block.
In order to facilitate the rivet passing through the guide block, particular lubricants are required within the pilot hole. These lubricants are selected to minimize chemical interaction between the lubricant or, rather, chemical attack by the lubricant against the guide block. Nonetheless, as these guide blocks are often used in repair situations deep within an underground mine where organic materials such as coal and methane gas are prevalent, the guide blocks are susceptible to chemical attack and damage from their environment alone.
The forces required in driving the rivets often result in damage to the guide blocks. As the lowest portion of the pilot hole is smaller than the pilot nail shank, forcing the shank through the hole causes at least cyclic damage. The rubber of the guide block is at least slightly deformable, and an improperly aligned driving tool used with a hammer, such as a single rivet driver and a 1-pound hammer, cause additional damage. However, of greater concern is the use of non-manual or powered driving tools, such as a pneumatic hammer.
A pneumatic hammer uses a series of blows to drive the rivet into and through belt and belt fasteners. Depending on the type of pneumatic hammer, a rivet may be secured with 3-5 large blows, or 3000-5000 smaller blows. In any event, this requires a large amount of air and produces impulse forces which cause significant damage to the guide block within the pilot holes. Within a finite number of uses, the guide block is useless because the damage to the interior of the pilot holes has not only removed the inward taper but also resulted in an outward taper.
As it is undesirable and expensive to simply treat the guide blocks as disposable, one approach for providing a guide for a pneumatic hammer is shown and described in U.S. Pat. No. 5,487,217, to Richardson, et al. The '217 patent shows use of a guide template having guide holes, the guide template being placed on the first side portion of the belt fastener and with the guide holes aligned with the openings in the belt fastener. The guide template is, when compared with a guide block, relatively thin and is formed of a generally rigid material. The driving tool is provided with an assembly barrel that is placed within or against the guide holes to assume a particular orientation therewith and, thus, provides the alignment function of the guide block, as described above. However, this guide template is best used with a tool having the assembly barrel or another alignment structure cooperating with the guide template to position the rivet for driving in the desired alignment. Conversely, this guide template is not as effective with manual tools that lack the described assembly barrel or another alignment structure. That is, a single driver is not effective utilized with the guide template as it may easily be misaligned.
There are many different typical installation scenarios for conveyor belts of the type described herein. The belts may be installed in an industrial or manufacturing plant. Power plants, such as coal-burning power plants, use conveyor belt systems to move coal from train hoppers to a coal pile, from the coal pile to grinding machines, and from the grinding machines to the ovens for burning the coal. The mining industry, in particular, makes extensive use of these heavy-duty conveyor belt systems, in both above-ground and below-ground installations.
In many installations, particular mining, belt scrapers are installed as part of the belt systems to remove matter that may become stuck to the belt. As the belts move at relatively high speeds, it is easy for the belt scrapers to damage the belts. In fact, a considerable amount of attention is being paid to designing belt scrapers that are able to give or flex when a scraper blade gets caught on a belt.
Together, these different installation scenarios present a number of issues. For belt systems including belt scrapers, breaking of the belt or damage thereto that is extensive enough to require repair is relatively common and expected. During this time, the belt must be out of service, halting the up-stream loading of material and halting the down-stream unloading of materials. For instance, a particular part of a coal mine maybe unable to send its ore out of the mine, or a portion of a commercial distribution center may come to a standstill while the belt is being repaired. This places a particular emphasis on the speed in which the belt is repaired.
In some instances, a belt fastener installation may be performed using a single driver, having a single drive rod. However, field installers generally believe this is a relatively slow and labor-intensive installation.
Multi-rivet drivers have been developed which field installers believe to be faster than the single driver. A known multi-rivet driver includes a head and a plurality of drive rods depending therefrom. The drive rods are inserted within a guide block positioned on top of the belt fastener. Each belt fastener has a pair of openings for each rivet, and the belt fastener has a plurality of such pairs for multiple rivets. For instance, the belt fastener may be secured with five rivets, and the multi-rivet driver has five drive rods used with five pilot holes of the guide block. As five rivets are simultaneously being driven, a larger hammer is used such as a four or five pound hammer. Regardless, multiple strokes are required to drive and swage the multiple rivets.
Commonly, installation or repair with a multi-rivet driver is performed by a pair of repairpersons, one who places the multi-rivet driver in the guide block and a second who swings the hammer. This presents a safety issue as the first repairperson may realize or believe the rivets are fully secured, prompting him or her to reach for the multi-rivet driver. The second repairperson, not having the same belief as to the securement of the rivets, may continue to swing the hammer during which time the first repairperson's hands maybe within the path of the hammer. This is known to cause injury to repairpersons, including the loss of fingers.
Early multi-rivet drivers were a unitary piece formed of steel, which resulted in a short-life span due to stress concentrations between a head or cap portion, which formed the anvil struck by the hammer, and the drive rods. In order to promote and extend the life of these tools, other multi-rivet drivers were developed that allow the drive rods to deflect relative to each other, thereby reducing the stress concentrations between the cap and the drive rods. In one form, the prior multi-rivet driver includes a rigid cap or anvil portion, and a deformable round insert or block for holding the drive rods, the block being secured within the cap. In use, however, these drivers produced uneven or unsatisfactory compression of the belt fastener on the belt, and rivets that are not fully driven and seated, each of which thereby concentrates stresses and belt tension forces on the rivets.
In greater detail, the opposed sides of the belt fastener are somewhat open prior to the rivets being driven in comparison to after having the rivets driven. This allows the belt end or splice end to be inserted between the sides of the belt fastener. The belt fastener is then compressed on the belt end as the rivets are driven. When the known multi-rivet driver having deflecting rods is used, the drive rods farthest from the bend of the belt fastener contact and begin to compress the belt fastener before the driver rods closest to the bend do so. As such, this portion of the belt fastener deforms somewhat, thereby reducing the ability of the belt fastener portions to be compressed into a parallel manner, instead being slightly arched. This reduces the load-sharing capabilities of the belt fastener by causing stress concentrations.
One option for overcoming the deficiencies of the manual tools is by using a pneumatic hammer which, by definition, requires a source of compressed air. In underground mining operations, certain difficulties are presented in using pneumatic tools. Subterranean mine air is somewhat different than surface air, containing a higher content of easily compressed gas, and so does not work well with pneumatic tools. Furthermore, because of the content of organic gasses such as methane in mine air, compressing this gas sometimes presents a safety concern. At the minimum, it is, at times, undesirable to run a fossil-fuel engine on a compressor in a mine for a variety of known reasons.
Because of the issues attendant to each of the different tools used for installing belt fasteners on belt splice ends, there has been a need for an improved belt fastening system and for improved tools for performing the operation.